1. Field of the Invention
The present invention relates to a flow rate measuring device that is installed at the inlet of a gas supply pipe in each household and is applied to a gas meter for measuring the gas flow rate. Specifically, the present invention relates to a technique for applying such a gas meter and identifying (specifying) a gas appliance in use in order to provide a new billing scheme and service, such as a fee by gas appliance, responsive to a used appliance type and its using method.
2. Background Art
A gas meter having a built-in gas flow rate measuring device is generally attached to the inlet of a gas supply line in each household. A billing scheme for setting a fee by gas appliance is implemented. When such a billing scheme is implemented using a conventional gas meter, a plurality of integrators connected to the gas meter are used. The integrated flow rate when the meter is used for a specific time period, and the integrated value when flow rate of a specific range is used are determined. In other words, flow rate by time zone and flow rate by flow rate zone are determined. A billing scheme is determined based on the integrated values.
An example of the billing scheme is described with reference to FIG. 20. In the billing scheme by gas appliance, a predetermined discount flow rate zone and a predetermined discount time zone are set in advance, and a discount is applied to the gas fees for flow rates corresponding to the discount flow rate zone and the discount time zone. Thus, the shaded areas shown in FIG. 20 correspond to the zones subject to the discount (for example, Patent Document 1).
However, this method falls into ambiguity in identifying an appliance. Therefore, it is difficult to perform fee setting, such as billing for a specific appliance, that is easier to understand and convenient for customers. Accordingly, a method for identifying a specific appliance is proposed as described below.
FIG. 21 shows a gas flow rate variation profile on activation of a certain gas appliance, and reference values (profile table) for performing profile matching based on the profile. Using the profile table, the variation of the flow rate value measured by a flow rate measuring device of a gas meter is always compared with the profile table and a matching value is extracted, thereby identifying a gas appliance (for example, Patent Document 2). In other words, the profile table is required to be prepared correspondingly to the flow rate variation profiles of a series of gases generated by combustion control of one gas appliance. The number of required profile tables is the total number of gas appliances used in each household.
In order to determine a stop of a gas appliance in the conventional configuration, flow rate variation is detected, and the occurrence or not of the stop of the gas appliance is determined. However, when a plurality of gas appliances are operated, it is difficult in some situations to identify which gas appliance has stopped. In other words, generally, when the operating flow rate of each gas appliance is accurately obtained, it can be identified which gas appliance has stopped by comparing the flow rate reduced by the stop with the operating flow rate. When the operating flow rates of two gas appliances are the same by chance, however, the possibility of incorrectly determining the stop increases. Therefore, the determining accuracy of the flow rate used in the gas appliance reduces, disadvantageously.    Patent document 1: Japanese Patent Unexamined Publication No. 2002-71421    Patent document 2: Japanese Patent Unexamined Publication No. 2003-149027